Phase shift method using phase shifter and frequency quadrupler, and device performing same

ABSTRACT

Disclosed are a phase shift method and a device performing same, the method comprising the steps of: shifting a phase of an input signal by a phase shifter, and up-converting, by a frequency quadrupler, a frequency of the input signal of which the phase has been shifted, by a multiplication coefficient (N). According to the phase shift method and the device performing same, it is possible to overcome a phase resolution decrease that occurs when passing through a frequency quadrupler in super high-frequency LO beamforming technology synchronized with a conventional frequency quadrupler.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a national stage application of International Application No.PCT/KR2021/020187, filed on Dec. 29, 2021, which claims the benefit ofKorean Patent Application No. 10-2020-0186702 filed on Dec. 29, 2020,and Korean Patent Application No. 10-2021-0176124 filed on Dec. 9, 2021,the entirety of each of which is incorporated herein by reference forall purposes.

TECHNICAL FIELD

The present disclosure relates to a phase shift method using a phaseshifter and a frequency multiplier and a device performing the same.

BACKGROUND ART

Recently, along with the increase of commercial needs for millimeterwave application systems, such as next-generation 5G wireless mobilecommunication networks and radar systems for autonomous vehicles andautonomous drones, phased array antennas and beamforming technologiesare getting attention for efficient implementation of high-speed datatransmission.

The beamforming technology may be divided into two main types dependingon its structure: a direct conversion structure that performsbeamforming at radio frequency (RF) and a superheterodyne structure thatperforms beamforming at the intermediate frequency (IF) or at the localoscillator (LO) frequency.

To obtain phase resolving in the range of 0° to 360° in beamforming, aphase shifter with phase resolution in the range of 0° to 360° may beused, or phase resolving of a phase shifter may be performed for asingle quadrant (e.g., 0° to 90°) and extended to the range of 0° to360° using a quadrupler.

The RF beamformer has an advantage in that it may be implemented in asimplified structure; since beamforming has to be performed in the radiofrequency (RF) band, however, insertion loss of a phase shifterincreases, which necessitates utilization of a high-gain amplifier toobtain satisfactory signal-to-noise ratio (SNR).

In the case of using the LO phase beamforming structure in theultra-high frequency band, an N-times frequency multiplier is generallyused. For example, if N=4 and the phase is controlled at f_(Lo)/4, phaseresolution of the phase shifter at the front of the multiplier has to ben+2 bits (360°/2^(n+2)) for a signal that has passed the quadrupler toobtain phase resolution of n-bits (360°/2^(n)). Therefore, achievinghigh phase resolution in the above structure requires finer phaseresolution, which is difficult to obtain.

PRIOR ART REFERENCES

(Patent 1) Korean laid-open patent No. 10-2011-0069660 (Jun. 23, 2011)

DISCLOSURE Technical Problem

An object of the present disclosure is to provide a phase shift methodcapable of overcoming a phase resolution decrease in the ultra-highfrequency LO beamforming technology based on a conventional frequencymultiplier when a signal passes the frequency multiplier and a devicethat performs the method.

However, the technical problem to be solved by the present disclosure isnot limited to the above but may be extended to other various problemsbelonging to the scope not departing from the technical principles anddomain of the present disclosure.

Technical Solution

A phase shift method according to one embodiment of the presentdisclosure comprises shifting phase of an input signal by a phaseshifter and up-converting frequency of the input signal with shiftedphase by a multiplication coefficient N by a frequency multiplier.

According to one aspect, phase resolution (°) of the phase shifter maybe determined by

$\frac{360{^\circ}}{2^{n} + x}$

In the equation above, n represents phase resolution (bits) of the phaseshifter, and x represents the number of shifted phase states.

According to one aspect, the total phase resolution (°) for a signalthat has passed the frequency multiplier may be determined by

$\frac{360{^\circ} \times N}{2^{n} + x}$

In the equation above, n represents phase resolution (bits) of the phaseshifter, x represents the number of shifted phase states, and Nrepresents the multiplication coefficient.

According to one aspect, the number of shifted phase states x may bedetermined to have a value at which phase overlapping does not occurregardless of the multiplication coefficient N.

According to one aspect, the frequency multiplier may include afrequency doubler.

According to one aspect, the method may further include amplifying thesize of an input signal with shifted phase by an amplifier after theshifting of phase of the input signal.

A phase shift device according to another embodiment of the presentdisclosure comprises a phase shifter shifting the phase of an inputsignal and a frequency multiplier up-converting the frequency of theinput signal with shifted phase by a multiplication coefficient N.

According to one aspect, the phase resolution (°) of the phase shiftermay be determined by

$\frac{360{^\circ}}{2^{n} + x}$

In the equation above, n represents phase resolution (bits) of the phaseshifter, and x represents the number of shifted phase states.

According to one aspect, the total phase resolution (°) for a signalthat has passed the frequency multiplier may be determined by

$\frac{360{^\circ} \times N}{2^{n} + x}$

In the equation above, n represents phase resolution (bits) of the phaseshifter, x represents the number of shifted phase states, and Nrepresents the multiplication coefficient.

According to one aspect, the number of shifted phase states x may bedetermined to have a value at which phase overlapping does not occurregardless of the multiplication coefficient N.

According to one aspect, the frequency multiplier may include afrequency doubler.

According to one aspect, the device may further include an amplifieramplifying the size of an input signal with shifted phase.

Advantageous Effects

The present disclosure provides the following effects. However, since itis not meant that a specific embodiment has to provide all of or onlythe following effects, the technical scope of the present disclosureshould not be regarded as being limited by the specific embodiment.

According to the phase shift method according to the embodiments of thepresent disclosure and the device performing the method, it is possibleto overcome a phase resolution decrease in the ultra-high frequency LObeamforming technology based on a conventional frequency multiplier whena signal passes the frequency multiplier.

Also, since phase shift of a signal is performed at a low frequency,insertion loss of the phase shifter may be reduced, which isadvantageous in securing the overall SNR of the system, and higher phaseresolution may be obtained compared to the prior art with a similarlevel of complexity while maintaining phase resolving in the range of 0°to 360°.

DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) and 1(b) illustrate a direct conversion structure and asuperheterodyne structure.

FIGS. 2(a), 2(b), and 2(c) illustrate a phase shift method using afrequency quadrupler.

FIGS. 3(a), 3(b), and 3(c) illustrate a decrease in phase resolutionwhen a phase shift method based on the superheterodyne structureutilizes a frequency doubler.

FIG. 4 is a flow diagram illustrating a phase shift method according toone embodiment of the present disclosure.

FIGS. 5(a), 5(b), and 5(c) illustrate phase resolution when the numberof shifted phase states x is −1.

FIGS. 6(a), 6(b), and 6(c) illustrate phase resolution when the numberof shifted phase states x is +1.

FIG. 7 illustrates the structure of a phase shift device according toone embodiment of the present disclosure.

MODE FOR DISCLOSURE

Since the present disclosure may be modified in various ways and mayprovide various embodiments, specific embodiments will be depicted inthe appended drawings and described in detail with reference to thedrawings.

However, it should be understood that the specific embodiments are notintended to limit the gist of the present disclosure; rather, it shouldbe understood that the specific embodiments include all of themodifications, equivalents, or substitutes belonging to the technicalprinciples and scope of the present disclosure.

Terms such as “first” and “second” may be used to describe variousconstituting elements, but the constituting elements should not belimited by the terms. The terms are introduced to distinguish oneelement from the others. For example, without departing from thetechnical scope of the present disclosure, a first element may bereferred to as a second element, and similarly, the second element maybe referred to as the first element.

If a constituting element is said to be “connected” or “attached” toother constituting element, the former may be connected or attacheddirectly to the other constituting element, but there may be a case inwhich another constituting element is present between the twoconstituting elements. On the other hand, if a constituting element issaid to be “directly connected” or “directly attached” to otherconstituting element, it should be understood that there is no otherconstituting element between the two constituting elements.

Terms used in the present disclosure are intended only for describing aspecific embodiment and are not intended to limit the technical scope ofthe present disclosure. A singular expression should be understood toindicate a plural expression unless otherwise explicitly stated. Theterm “include” or “have” is used to indicate existence of an embodiedfeature, number, step, operation, element, component, or a combinationthereof; and should not be understood to preclude the existence orpossibility of adding one or more other features, numbers, steps,operations, elements, components, or a combination thereof.

Unless defined otherwise, all the terms used in the present disclosure,including technical or scientific terms, provide the same meaning asunderstood generally by those skilled in the art to which the presentdisclosure belongs. Those terms defined in ordinary dictionaries shouldbe interpreted to have the same meaning as conveyed in the context ofrelated technology. Unless otherwise defined explicitly in the presentdisclosure, those terms should not be interpreted to have ideal orexcessively formal meaning.

In what follows, with reference to appended drawings, preferredembodiments of the present disclosure will be described clearly and indetail so that those skilled in the art to which the present disclosurebelongs may implement the present disclosure easily.

FIGS. 1(a) and 1(b) illustrate a direct conversion structure and asuperheterodyne structure.

FIG. 1(a) illustrates the direct conversion structure that performsbeamforming in the radio frequency (RF) band, and FIG. 1(b) illustratesthe superheterodyne structure that performs beamforming at theintermediate frequency (IF) or local oscillator (LO) frequency.

The beamformer based on the direct conversion structure has an advantagein that it may be implemented in a simplified structure; sincebeamforming has to be performed in the radio frequency (RF) band,however, insertion loss of a phase shifter increases, which necessitatesutilization of a high-gain amplifier to obtain satisfactorysignal-to-noise ratio (SNR).

When a frequency multiplier is used to increase the frequency after asignal passes a phase shifter in the superheterodyne structure, allcases of using a frequency multiplier, including a doubler but excludinga tripler, obtain phase resolution lower than that of the phase shifter.When the phase resolution of the phase shifter is n bits (360°/2^(n)),and a signal passes a frequency multiplier that includes a frequencydoubler once, the phase resolution is reduced to n−1 bits(360°/2^(n−1)).

FIGS. 2(a), 2(b), and 2(c) illustrate a phase shift method using afrequency quadrupler.

Referring to FIGS. 2(a), 2(b), and 2(c), the phase shift method using afrequency quadrupler performs (PS of FIG. 2(a)) phase resolving of thephase shifter on a single quadrant (e.g., 0° to 90°)and extends thephase shift to the range of 0° to 360° using the frequency quadrupler(X4 block of FIG. 2(a)).

For example, to obtain the phase resolution as shown in FIG. 2(c), phaseresolving is performed in the single quadrant, as shown in FIG. 2(b),which is subsequently extended to the range of 0° to 360° using afrequency quadrupler. Here, to obtain the phase resolution of 3 bits(45°), phase resolution of 5 bits (11.25°) is required in the singlequadrant before a signal passes the frequency quadrupler.

In other words, for a signal which has passed the frequency quadruplerto obtain the phase resolution of n bits (360°/2^(n)) according to thestructure based on the frequency quadrupler, the phase resolution of thephase shifter has to be n+2 bits (360°/2^(n+2)). Therefore, achievinghigh phase resolution in the above structure requires finer phaseresolution, which is difficult to obtain.

FIGS. 3(a), 3(b), and 3(c) illustrate a decrease in phase resolutionwhen a phase shift method based on the superheterodyne structureutilizes a frequency doubler.

When a frequency multiplier is used to increase the frequency after asignal passes a phase shifter in the superheterodyne structure, allcases of using a frequency multiplier, including a doubler but excludinga tripler, obtain phase resolution lower than that of the phase shifter.When the phase resolution of the phase shifter is n bits (360°/2^(n)),and a signal passes a frequency multiplier that includes a frequencydoubler once, the final phase resolution is reduced to n−1 bits(360°/2^(n−1)); when a signal passes a frequency multiplier thatincludes the frequency doubler a times, the phase resolution is reducedto n−a bits (360°/2^(n−a)).

For example, as shown in FIG. 3(a), assuming that a frequency doubler isapplied to the signal which has passed the phase shifter of 4 bits(22.5°), the phase resolution is reduced to 3 bits (45°) when afrequency multiplier (N=2) that includes a frequency doubler once, whilethe phase resolution is reduced to 2 bits (90°) when the frequencymultiplier (N=4) that includes the frequency doubler twice, as shown inFIG. 3(c).

FIG. 4 is a flow diagram illustrating a phase shift method according toone embodiment of the present disclosure.

Referring to FIG. 4 , in the S410 step, the phase shifter shifts thephase of an input signal. The phase shifter may shift the phase of aninput signal through an electrical or mechanical means. The phaseresolution (°) of the phase shifter may be expressed by Eq. 1.

$\begin{matrix}\frac{360{^\circ}}{2^{n} + x} & \lbrack {{Eq}.1} \rbrack\end{matrix}$

In Eq. 1, n represents phase resolution (bits) of the phase shifter, andx represents the number of shifted phase states.

In the S430 step, an amplifier amplifies the size of the input signalwith shifted phase. The S430 step may be selectively applied accordingto the required signal size.

In the S450 step, the frequency multiplier up-converts the frequency ofthe input signal with shifted phase by a multiplication coefficient N.The total phase resolution (°) for a signal that has passed thefrequency multiplier may be determined by Eq. 2.

$\begin{matrix}\frac{360{^\circ} \times N}{2^{n} + x} & \lbrack {{Eq}.2} \rbrack\end{matrix}$

In Eq. 2, n represents phase resolution (bits) of the phase shifter, xrepresents the number of shifted phase states, and N represents themultiplication coefficient.

Referring to Eq. 2, when the number of shifted phase states x is 0, theactual value of the total phase resolution is reduced as phases overlapdepending on the multiplication coefficient N, as shown in FIGS. 3(a),3(b), and 3(c), except for the case in which a frequency tripler isemployed (i.e., N≠3, 9, . . . ).

Therefore, if the number of shifted phase states x is determined to havea value at which phase overlapping does not occur regardless of themultiplication coefficient N in Eq. 2, the total phase resolution may bekept to its original value.

FIGS. 5(a), 5(b), and 5(c) illustrate phase resolution when the numberof shifted phase states x is −1.

FIG. 5(a) shows the phase resolution (°) of the phase shifter accordingto Eq. 1 when the phase resolution (bits) of the phase shifter is 4bits, FIG. 5(b) shows the total phase resolution (°) according to Eq. 2when a frequency multiplier (N=2) including a frequency doubler once isused, and FIG. 5(c) shows the total phase resolution (°) according toEq. 2 when a frequency multiplier (N=4) including a frequency doublertwice is used.

Different from the example of FIG. 4 , when the number of shifted phasestates x is −1, it may be checked that phase overlapping does not occureven if a frequency multiplier including a frequency doubler is used;therefore, the total phase resolution may be kept to its original value.

FIGS. 6(a), 6(b), and 6(c) illustrate phase resolution when the numberof shifted phase states x is +1.

FIG. 6(a) shows the phase resolution (°) of the phase shifter accordingto Eq. 1 when the phase resolution (bits) of the phase shifter is 4bits, FIG. 6(b) shows the total phase resolution (°) according to Eq. 2when a frequency multiplier (N=2) including a frequency doubler once isused, and FIG. 6(c) shows the total phase resolution (°) according toEq. 2 when a frequency multiplier (N=4) including a frequency doublertwice is used.

In the same way as described with reference to FIGS. 5(a), 5(b), and5(c), when the number of shifted phase states x is 1, it may be checkedthat phase overlapping does not occur even if a frequency multiplierincluding a frequency doubler is used; therefore, the total phaseresolution may be kept to its original value.

The conventional phase shifter requires a controller with a highernumber of control bits to produce, for example, 4-bit phase resolution(22.5°). The aforementioned feature may be noticed by examining thex-axis and y-axis values of 16 points corresponding to the 4-bit phasesignal in FIG. 3(a). The x-axis and y-axis values are not equally spacedfrom each other. In other words, to create 16 phase states, an actualcontroller needs to have high resolution corresponding to the minimumrequired control signal (voltage).

Meanwhile, according to the phase shift method based on one embodimentof the present disclosure, the x-axis and y-axis values of 16 pointscorresponding to the 4-bit phase signals shown in FIG. 5(a) and FIG.6(a) are not significantly different from the x-axis and y-axis valuesof 16 points corresponding to the 4-bit phase signal shown in FIG. 3(a).Therefore, according to the phase shift method based on one embodimentof the present disclosure, phase control with higher resolution than theconventional phase shifter may be performed without designing anadditional controller.

FIG. 7 illustrates the structure of a phase shift device according toone embodiment of the present disclosure.

Referring to FIG. 7 , the phase shift device 700 according to oneembodiment of the present disclosure may include a phase shifter 710, anamplifier 730, and a frequency multiplier 750.

The phase shifter 710 shifts the phase of an input signal. The phaseshifter 710 may shift the phase of an input signal through an electricalor mechanical means. The phase resolution (°) of the phase shifter maybe expressed by Eq. 1.

The amplifier 730 amplifies the size of the input signal with shiftedphase. The amplifier 730 may be selectively used according to therequired signal size.

The frequency multiplier 750 up-converts the frequency of the inputsignal with shifted phase by a multiplication coefficient N. The totalphase resolution (°) for a signal that has passed the frequencymultiplier may be determined by Eq. 2.

Referring to Eq. 2, when the number of shifted phase states x is 0, theactual value of the total phase resolution is reduced as phases overlapdepending on the multiplication coefficient N, as shown in FIGS. 3(a),3(b), and 3(c), except for the case in which a frequency tripler isemployed (i.e., N≠3, 9, . . . ).

Therefore, if the number of shifted phase states x is determined to havea value at which phase overlapping does not occur regardless of themultiplication coefficient N in Eq. 2, the total phase resolution may bekept to its original value.

The phase shift method according to the present disclosure may beimplemented in the form of computer-readable codes in acomputer-readable recording medium. The computer-readable recordingmedium includes all kinds of recording devices storing data that may beread by a computer system. Examples of a computer-readable recordingmedium include a Read Only Memory (ROM), a Random Access Memory (RAM), amagnetic tape, a magnetic disk, a flash memory, and an optical datastorage device. Also, the computer-readable recording medium may bedistributed over computer systems connected to each other through acomputer communication network and may be stored and executed asreadable codes in a distributed manner.

In the above, the present disclosure has been described with referenceto appended drawings and embodiments, but the technical scope of thepresent disclosure is not limited to the drawings or embodiments.Rather, it should be understood by those skilled in the art to which thepresent disclosure belongs that the present disclosure may be modifiedor changed in various ways without departing from the technicalprinciples and scope of the present disclosure described by the appendedclaims below.

DESCRIPTIONS OF SYMBOLS

-   -   700: Phase shift device    -   710: Phase shifter    -   730: Amplifier    -   750: Frequency multiplier

1. A phase shift method comprising: shifting phase of an input signal bya phase shifter; and up-converting frequency of the input signal withshifted phase by a multiplication coefficient N by a frequencymultiplier.
 2. The method of claim 1, wherein phase resolution (°) ofthe phase shifter is determined by $\frac{360{^\circ}}{2^{n} + x}$wherein n represents phase resolution (bits) of the phase shifter, and xrepresents the number of shifted phase states.
 3. The method of claim 2,wherein the total phase resolution (°) for a signal that has passed thefrequency multiplier is determined by$\frac{360{^\circ} \times N}{2^{n} + x}$ wherein n represents phaseresolution (bits) of the phase shifter, x represents the number ofshifted phase states, and N represents a multiplication coefficient. 4.The method of claim 3, wherein the number of shifted phase states x isdetermined to have a value at which phase overlapping does not occurregardless of the multiplication coefficient N.
 5. The method of claim1, wherein the frequency multiplier includes a frequency doubler.
 6. Themethod of claim 1, further comprising: amplifying the size of an inputsignal with shifted phase by an amplifier after the shifting of phase ofthe input signal.
 7. A phase shift device comprising: a phase shiftershifting the phase of an input signal; and a frequency multiplierup-converting the frequency of the input signal with shifted phase by amultiplication coefficient N.
 8. The device of claim 7, wherein phaseresolution (°) of the phase shifter is determined by$\frac{360{^\circ}}{2^{n} + x}$ wherein n represents phase resolution(bits) of the phase shifter, and x represents the number of shiftedphase states.
 9. The device of claim 8, wherein the total phaseresolution (°) for a signal that has passed the frequency multiplier isdetermined by $\frac{360{^\circ} \times N}{2^{n} + x}$ wherein nrepresents phase resolution (bits) of the phase shifter, x representsthe number of shifted phase states, and N represents a multiplicationcoefficient.
 10. The device of claim 9, wherein the number of shiftedphase states x is determined to have a value at which phase overlappingdoes not occur regardless of the multiplication coefficient N.
 11. Thedevice of claim 7, wherein the frequency multiplier includes a frequencydoubler.
 12. The device of claim 7, further comprising: an amplifieramplifying the size of an input signal with shifted phase.